I own 2 mountain bikes, 0 gravel bikes and want to roll a few gravel races this summer.

This is just for fun and a challenge and some excuses to wrench on a bike. I’m looking for some guidance on bike selection and mods to let me try my hand at 3 gravel races this summer (50mi, 70 mi and 100mi).

I have 2 mountain bikes and have done MTB races up to 35 mi. I’m middle aged and not trying to win. Just have fun and experience a different style of biking.

I have 2 mtb: a Nimble 9 (steel) hard tail with a 150mm fork (pictured) and an Ibis Ripley carbon (130mm F / 120mm R)

So my questions are
1. which bike would be better (obviously neither is best) for long gravel rides.
2. Can you help me make a prioritized list of tweaks to either bike to make it more reasonable on long gravel rides?

I’m thinking the Ibis + some 2.25 MTB tires is a good start – currently it has some like 2.5s on is. Is switching to a drop bar setup worthwhile? I do love the look of a drop bar mtb… But maybe just a MTB bar cut down to like 680 instead of my usual 750+ is enough?

Any other suggestions? Nobody close by rents gravel bikes.

Thanks and Ride On!